The Toyota Sienna V6 uses the serpentine belt, also called the multi-accessory drive belt, to control all engine accessories: the power steering, air conditioner compressor, water pump and the alternator. Located at the front of the crankshaft, the serpentine belt winds around the pulleys connected to the various accessories and ultimately around a tension pulley that keeps the belt at the correct contact tension so that all the engine accessories engage properly. Adjusting the serpentine belt on a Sienna V6 is a simple do-it-yourself project that requires the proper sized wrench.

Check to ensure the Sienna V6's engine is cold, then make sure the car is in park, the ignition is off and the key is removed from the ignition to prevent any possibility of the engine engaging during the belt adjustment.

Find the tensioner pulley, the main pulley that controls the serpentine alternator belt, and fit a 1/2-inch wrench over the tensioner bolt on the outside of the pulley.

Turn the wrench slowly to the right and watch the belt to determine if the slack is decreasing as the tensioner is tightened. Keep turning, or tightening, the bolt until all the slack in the belt is gone and the belt is snug, but not stretched, against the tensioner pulley wheel.

Remove the wrench and close the hood.

Start the engine, as an engine that starts without problem indicates that the serpentine belt's tension is sufficient to engage the alternator. Listen for any squealing of the belt, which indicates that additional tightening is needed.

Repeat Steps 1 through 4, if necessary, until the engine starts without incident and the belt is silent.

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About the Author

An attorney for more than 18 years, Jennifer Williams has served the Florida Judiciary as supervising attorney for research and drafting, and as appointed special master. Williams has a Bachelor of Arts in communications from Jacksonville University, law degree from NSU's Shepard-Broad Law Center and certificates in environmental law and Native American rights from Tulsa University Law.